Multichamber tubular diaphragm pump

ABSTRACT

A tubular diaphragm pump, particularly useful for pumping corrosive fluids at relatively high-uniform pressures, such as in reverse osmosis systems. A work fluid is driven in phased sequence inside a plurality of sealed tubular diaphragm pump chambers arranged in parallel flow paths. The respective diaphragms expand into their associated pump chambers to force the fluid being pumped through the system. Pressure-responsive check valves at the inlet and outlet of each pump chamber open and close in phased sequence to control flow. A drive mechanism which is sealed off from the fluid being pumped is provided to drive the work fluid which flexes the diaphragms. The flexible tubular diaphragms are disposed on cylindrical members having wider end portions and perforated intermediate wall portions of lesser diameter than the adjacent end portions. The cylindrical members each have a central chamber which communicates with the internal surface of the associated tubular diaphragm through the perforations in the intermediate wall portion. Each central chamber is also in communication with a piston chamber containing a reciprocating drive piston. The pistons are connected to reciprocate in phased sequence. The central chambers and the piston chambers are filled with a hydraulic work fluid which flexes the tubular diaphragms when the pistons reciprocate. In at least one embodiment, the cylindrical members supporting the tubular diaphragms each include an integral end extension defining the piston chamber. The cylindrical members also serve as tie rods for the pump assembly.

United States Patent Goeldner [s41 MULTICHAMBER TUBULAR DIAPHRAGM PUMP 72] Inventor: Richard W. Goeldner, New Berlin, Wis.

[73] Assignee: Aqua-Chem, Inc.

[22] Filed: Nov. 21, 1969 [21] Appl.No.: 878,715

[52] US. Cl ..4l7/389, 417/473, 417/394, 4 l 7/539 [51] int. Cl ..F04b 9/08, F04b 35/02, F04b 45/02, F04b 43/06 [58] Field of Search ..4l7/339, 340, 342, 347, 289

Primary Examiner-Robert M. Walker Attorney-F red Wiviott and Ralph G. Hohenfeldt [451 Jan. 25, 1972 [5 7] ABSTRACT A tubular diaphragm pump, particularly useful for pumping corrosive fluids at relatively high-uniform pressures, such as in reverse osmosis systems. A work fluid is driven in phased sequence inside a plurality of sealed tubular diaphragm pump chambers arranged in parallel flow paths. The respective diaphragms expand into their associated pump chambers to force the fluid being pumped through the system. Pressureresponsive check valves at the inlet and outlet of each pump chamber open and close in phased sequence to control flow. A drive mechanism which is sealed off from the fluid being pumped is provided to drive the work fluid which flexes the diaphragms.

The flexible tubular diaphragms are disposed on cylindrical members having wider end portions and perforated intermediate wall portions of lesser diameter than the adjacent end portions. The cylindrical members each have a central chamber which communicates with the internal surface of the associated tubular diaphragm through the perforations in the intermediate wall portion. Each central chamber is also in communication with a piston chamber containing a reciprocating drive piston. The pistons are connected to reciprocate in phased sequence. The central chambers and the piston chambers are filled with a hydraulic work fluid which flexes the tubular diaphragms when the pistons reciprocate. In at least one embodiment, the cylindrical members supporting the tubular diaphragms each include an integral end extension defining the piston chamber. The cylindrical members also serve as tie rods for the pump assembly.

l Claims, 9 Drawing Figures PATENTEB am 55912 WEE]? 1 BF 2 FIG.3

- y llluwn. --.--.m. ......!I III! I RICHARD W. GOELDNER INVENTOR ATTORNEY 1 MULTICIIAMBER TUBULAR DIAPHRAGM PUMP BACKGROUND OF THE INVENTION There are numerous applications in which an industrial process requires that a corrosive fluid be pumped from one location to another. If simple mechanical pumps are used, such as centrifugal pumps, rotary displacement pumps, and turbine pumps, the corrosive fluid comes into direct contact with the mechanical parts of the pump, such as the impeller blades. Shaft seals for the rotating parts of the pumps are also sensitive to attach by the corrosive fluids. Such pumps can be made with corrosion-resistant internal parts and seals, but at considerably greater cost. When pumping corrosive liquids, such as salt water, the mechanical parts of pumps should be isolated from the corrosive liquid if possible. It is particularly important in such applications to provide a pump which is easily maintained, and which will give good service at high pump pressures, particularly in reverse osmosis systems for liquid purification, where relatively high pressures are required to push the solvent through the reverse osmosis membrance, and in which pump repairs often must be effected in remote field locations.

FIELD OF THE INVENTION A reverse osmosis system which can utilize the multichamber tubular diaphragm pump of this invention is described in US. Pat. No. 3,341,024, issued Sept. 12, 1967 to E. Lowe et al. The novel pump of this invention has many additional application, but its advantages are particularly evident for pumping a corrosive liquid at relatively high pressures.

DESCRIPTION OF THE PRIOR ART Many pumping devices have been proposed for moving corrosive fluids and most of these are relatively complex, and therefore expensive to manufacture. The so-called peristaltic pumps are useful for moving fluidized solids, but at relatively low velocities. In addition, in a peristaltic pump, the direct mechanical flexing of the flexing tubular member causes wear and short pump life. Because of such limitations, apparatus of this type is impractical for many applications.

Other types of flexing tube pumps have also been proposed. In one such device, a work fluid surrounds a diaphragm, and is caused to oscillate to flex the diaphragm. Since the fluid being pumped is inside the flexible tube, the flexing action and the sealing of the tubular diaphragm is more complicated. In one case, the tube ends are built up with integral reinforcing flanges and sealed to the inlet and outlet ends of the pump chamber. Disassembly for maintenance is difficult in such a construction, thereby limiting the possible applications to locations where specialized maintenance service is available.

In another arrangement, a plurality of tubular diaphragms are disposed in series on a single, axial mounting means. The diaphragms are simultaneously oscillated by a single oscillating means thereby accentuating the rapid pressure changes. Such a system is not useful where a relatively constant, high pressure pumping capacity is required.

SUMMARY OF THE INVENTION Applicants parallel path, flexible diaphragm pump includes a plurality of tubular diaphragms which are each disposed in the fluid being pumped in a portion of the respective parallel pump chambers and each tubular diaphragm is actuated by a work fluid disposed in work fluid chambers defined inside the respective diaphragms. The work fluid is driven by a plurality of pistons reciprocating in phased sequence in cylinders in direct fluid communication with the work fluid chambers, each piston pushing its associated diaphragm out against the fluid being pumped through the associated pump chamber to maintain a uniform high-pressure flow through the system. Each diaphragm is disposed around a perforated intermediate portion of an elongated tubular support. The tubular support may include an integral and extension defining the piston 2 cylinder. Sealing of the diaphragms is not a serious problem, because they are stretched over the tubular supports and clamped against the supports at their respective end portions. The diaphragms can be fabricated from constant diameter tubular material if suitable end clamps are used. If desired, the tubular diaphragms can be provided with specially designed, enlarged end portions, thereby eliminating the need for clamps.

When the pump is used in combination with a reverse osmosis solvent separation system, it is important that the pump have a relatively high, essentially constant flow pressure characteristic. This is obtained by the phased sequence drive system of the invention, in which each diaphragm is oscillated in sequence by its associated piston to maintain the high pressure required to push raw water through a reverse osmosis membrane. For this application, it is important that the liquid pressure be maintained very close to the design pressure to maintain a desired flow velocity. The flow velocity is required especially when the flow stream parallels the membrane surface as with a membrane cast inside a tubular support member. The flow velocity tends to maintain turbulent liquid flow along the surface of the reverse osmosis membrane to keep the minute pores of the membrane clear.

The reciprocating action of the pistons is produced by a crankshaft connected to a suitable prime mover, such as an electric motor. In some applications in remote locations, it may be necessary to use a fossil-fuel-driven motor, but the important feature is that the crankshaft assures phased driving of the pistons and sequential flexing of the respective tubular diaphragms.

One important feature of the pump unit of the invention is the tubular support means for each tubular diaphragm which limits the inward contraction of the diaphragm, thereby preventing nonuniform flexing and premature wear. The end portions of the tubular supports are not perforated and are larger in diameter to provide a sealing surface for the associated ends of the diaphragms. The respective pump chambers comprise tubular housings, surrounding the perforated portions of the tubular supports. The tubular housings are tied to the valve manifold block by end extensions of the tubular support.

The concentric tubular arrangement of the perforated tubular support, the tubular diaphragm and the tubular housing provide a compact, easily maintained assembly. The individual diaphragm units are designed with a high-ratio length to diameter to further improve the operating economies to be realized with this unit. The increased length reduces the range of diaphragm stretch required and the smaller diameter substantially minimizes the burst pressure requirements, allowing use of a relatively thin walled tubular housing.

This invention provides an improved, long service multichamber tubular diaphragm pump which is particularly useful for pumping corrosive fluids under relatively high and constant pressures. The system enhances the tubular diaphragm pump concept by providing a plurality of integral phasesequenced pumps which cooperate to provide an cfficient and practical pumping system, particularly useful for liquid purification by reverse osmosis.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view with some parts broken away and some parts shown in phantom showing the multichamber pump of the invention;

FIG. 2-4 are enlarged side sectional views of one pumping chamber of the invention illustrating the pumping action;

3 DETAILED DESCRIPTION OF THE INVENTION A pump assembly 1 is shown in FIG. I of the drawing attached to a drive assembly 2. In the example illustrated, the drive assembly 2 includes a crankshaft 3 having a plurality of cranks 4 thereon and connected to a drive pulley 5. The drive pulley 5 is driven by an endless belt 6 which is mounted on the pulley 5 and a motor pulley 7 on a drive motor 8.

A plurality of piston rods 9 are each connected at their respective outer ends to an associated crank 4. The inner ends of each piston rod 9 are connected to an associated piston 10 to reciprocate the pistons 10 in phased sequence.

A plurality of tubular housings 11 are provided, each extending outwardly from a common valve manifold 12. One of the tubular housings 11 is associated with each piston 10, and

each housing 11 includes an inner end 13 and an outer end 14. A tubular support rod 15 is disposed in, and extends through, each housing 11, and through the valve manifold ll2. The support rods 15 each include a perforated intermediate portion 16 of smaller diameter, and enlarged diameter portions 17 immediately adjacent the intermediate portion 16. A tubular diaphragm 18 is disposed surrounding the perforated intermediate portion 16 of each support rod 15 and is held in place thereon by clamps l9 sealing the diaphragm 18 to the respective enlarged diameter portions 17.

' The support rods 15 also include outer extensions 20, and enlarged inner extensions 21. The inner extensions 21 pass through the manifold 12, and each has a piston chamber 22 formed therein enclosing the associated piston 10. The piston chambers 22 normally contain work fluid 23 and commu nicate with work fluid chambers 24 in the perforated intermediate portions 16. As can be seen in FIGS. 24, the work fluid is forced out through perforations 25 from the work fluid chamber 24 to expand the respective tubular diaphragms [8 in phased sequence, thereby displacing the pumped fluid from the tubular housings 11.

In the embodiment shown, work fluid 23 is disposed inside the tubular diaphragms l8, and the liquid being pumped is outside the diaphragms 18. This arrangement is preferred, but can be reversed. In addition the diaphragms 18 may take other shapes, such as flexible bags or sheetlike members. The important function of the diaphragms is to isolate the work fluid and the driving mechanism from the fluid being pumped.

An inlet check valve 26 and an outlet check valve 27 are associated with each tubular housing 11 to insure a steady flow of fluid under high pressure through the system with substantially no backflow. Pumped fluid flows through the system under pressure as each piston 10 moves through its compression stroke into the respective piston chamber 22, thereby expanding the associated tubular diaphragm 18. The outlet valve 26 opens in response to the inward movement of the piston 10,

which causes the work fluid 23 to expand the tubular diaphragm l8 outwardly, thereby pushing the fluid being pumped through the outlet valve 27. The inlet valve 26 is closed at this time to insure maximum pumping pressure. As the piston 10 commences its return stroke, the outlet valve 27 closes, and the inlet valve 26 opens in response to the decrease in pressure caused by the contraction of the tubular diaphragm 18 in the tubular housing 11. Additional fluid rushes into the housing 11, and as the piston 10 repeats the compression stroke, the cycle is repeated.

FIGS. 2-4 show the tubular diaphragm 18 and the piston 16 in the three main positions of the cycle as follows:

1. FIG. 2piston 10 shown in compression stroke, tubular diaphragm l8 expanded, outlet valve 27 open, inlet valve 26 closed;

2. FIG. 3-piston 10 at beginning of return stroke, diaphragm '18 returning to normal dimensions, inlet valve 26 opening and outlet valve 27 closing;

3. FIG. 4-piston 10 at end of return stroke, diaphragm l8 at normal dimensions, outlet valve 27 closed, and inlet valve 26 fully open.

- As each piston 10 reciprocates in its respective piston chamber 22, each outlet valve 26 successively supplies fluid being pumped to manifold outlet chamber 28. The fluid collected under pressure in the manifold outlet chamber 28 then flows out under pressure through any suitable conduit, such as tube 29, to the associated system, such as a reverse osmosis liquid purification system.

As can be seen in FIG. 2, thetubular support rod 15 has an annular shoulder 30 which is drawn into tight abutment with wall 31 of the manifold 12 by tightening end cap 32 down on the outer end of the tubular support rod 15 against the tubular housing 11. In this arrangement, the support rod 15 not only defines the piston chamber 22, the work fluid chamber 24, and the support means for the diaphragm 18, it also serves as a tie rod means for the complete pump assembly 1.

For bleeding air from the portions of the system containing work fluid 23, an elbow 33 is threadably received in the outer end extension 20 of the support rod 15 which extends through the end cap 32. Upper end 34 of each elbow 33 is above the level of work fluid 23 in the piston chambers 22 and the cham bers 24 to insure complete air removal from the system. Elbows 33 are normally closed by threaded plugs 34. 7

Another embodiment of the multichamber tubular diaphragm pump of the invention is illustrated in FIGS. 5-9. For purposes of clarity, the piston rods, crankshaft and drive assembly are not shown.

In pump assembly 35 shown in FIGS. 5-9 a plurality of pistons 36 are reciprocably disposed in piston chambers 37 in fluid communication with chambers 38 in perforated tubular support rods 39. As with the previously described apparatus, tubular diaphragms 40 are disposed on each support rod 39 and sealed at the respective ends by means such as clamps 41.

The sequential pumping action in each tubular housing 42 of the pump assembly 35 is clearly shown in FIG; 5 of the drawings, in which the effect of the position of the respective pistons 36 on the condition of the tubular diaphragms 40 can be seen. Starting at the top of FIG. 5, the piston 36 in the intermediate position causes the associated tubular diaphragm 40 to commence expansion. When the piston 36 is at the inner end of its stroke, the associated diaphragm 40 is fully expanded, forcing the liquid being pumped from the tubular housing 42 through associated outlet check valve 43. The bottom piston 36 in FIG. 5 is shown at the outer end of its stroke, and its associated diaphragm 40 is disposed adjacent the associated tubular support rod 39 in its minimum volume dimension condition. At this point in the cycle, the corresponding inlet check valve 44 is open and new liquid enters the associated tubular housing chamber 42 to then be forced on through the system on the next compression stroke of the piston 36.

As can be seen in FIGS. 5 and 6, tubular housing 42 extends between an inlet manifold 45 and an outlet manifold 46, held together by the tubular support rod 39. The inlet manifold 45 includes an inlet chamber 47 and a plurality of inlet check valves 44, one valve 44 being associated with tubular housing 42 to provide controlled liquid communication between the inlet chamber 47 and the respective tubular housing 42.

The outlet manifold 46 is disposed at the second end of the tubular housing 42 and includes the outlet check valves 43 which are in liquid communication with the corresponding tubular housings 42 through short liquid passages 49 in the manifold 46. A central outlet chamber 50 is provided downstream from the outlet check valves 43 in which the parallel flow liquid is collected and pumped on through an outlet conduit 51 to the point of use.

As can be seen in both FIGS. 5 and 6, the tubular support rods 39 extend out through the outlet manifold 46, and a retaining nut 52 is threaded down on outer ends 53 of the rods 39 to tighten the whole assembly together, the tubular support rods 39 serving as tie rods. The outer end 53 is fitted with an elbow 54 and plug 55- similar to that described above in connection with FIGS. 24.

As shown in FIG. 4, the work fluid is maintained at the proper operating levels in the respective piston chambers 22 by means of a bleed passage 56 associated with each piston chamber 22. The bleed passages 56 are connected by means of fluid conduits 57 to a work fluid reservoir 58, which is normally disposed at a higher level than the pump assembly I, and which is subjected to at least atmospheric pressure through ports 59.

As shown in FIG. 4, the bleed passage 56 is opened into the piston chamber 22 when the piston is at the outer end of the stroke. If there is any need to replenish work fluid in the piston chamber 10 or in the associated perforated intermediate portions 17 of the tubular support rods 16, the work fluid flows by gravity into the system under the influence of vacuum produced in the piston chamber.

Some work fluid leaks past the pistons 10 along piston chamber 22 into crankshaft casing 60. As shown in FIG. 4, a short passage 61 connects the upper portion of the crankshaft casing 60 to the work fluid reservoir 58. Observation of the fluid level in the reservoir 58 will establish whether the system requires additional work fluid 23. In the present embodiment of the invention, the work fluid comprises a liquid oil having good lubricating properties to reduce friction between the relatively moving parts of the pump and drive assemblies. Other work fluids can be used in certain circumstances, and friction can be reduced by other means, such as teflon coating of the opposing moving surfaces.

There are many modifications of this new multichamber tubular diaphragm pump which can be made, as determined by the particular application. Many such modifications suggest themselves, depending on the particular operation conditions.

In one alternate construction, the work fluid can be kept separate from the lube oil for the crankshaft, and other parts of the drive system by suitable sealing means. It is also contemplated that the oil in the reservoir could be replenished by means of a slinger disposed on the crankshaft. In this embodiment, it is not necessary to keep the crankcase full of oil. The above-described embodiments are intended to disclose one contemplated use, for which the apparatus is particularly well adapted.

I claim:

1. A diaphragm pump comprising an elongate tubular member, a cylinder formed in a first portion of said member, a plurality of apertures formed in a second portion of said member, a tubular diaphragm disposed over the second portion of said member and affixed thereto in a sealed relation adjacent the margins thereof, a housing surrounding said second portion and having inlet and outlet means, a work fluid disposed within said member, a piston disposed within said cylinder for reciprocating movement therein, valve means associated with said input and output means for controlling the flow of a pumped fluid outwardly from said housing through said outlet means as said piston moves toward said diaphragm to expand the same and inwardly through said inlet means when said piston moves away from said diaphragm.

2. The pump set forth in claim 1 and including a pump body, said tubular member and said housing being affixed to said pump body and extending therefrom, said inlet and outlet means comprising port means formed in said pump body and communicating with the interior of said housing.

3. The pump set forth in claim 2 wherein said cylinder is formed in one end of said member which is affixed to said pump body, said second portion extending away from said housing, operating means for moving said piston within said cylinder.

4. The pump set forth in claim 3 wherein said pump body includes a central body member, a first one of said port means being formed in a first portion of said central body member and the second port means being formed in a second portion thereof and first and second body members secured to said central body member and being disposed over said first and second port means respectively.

5. The pump set forth in claim 3, and including a work fluid reservoir, and passage means including a work fluid port for coupling said cylinder to said reservoir, said work fluid port being uncovered by said piston as the latter moves toward a terminal position away from said diaphragm and being covered by said piston as the same moves toward said diaphragm whereby said cylinder will refill with work fluid during each stroke of said piston.

6. The pump set forth in claim 5, wherein said work fluid reservoir is connected to said operating means for lubricating the same wherein leakage of work fluid past said piston also provides lubricating said piston and operating means.

7. The pump set forth in claim 5 and including three pump units, said drive means being operative to move the piston of said pump means in a balanced phase sequence of l20.

8. A multiple unit pump assembly, each pump unit including an elongate tubular member, a cylinder formed in a first portion of each member and a plurality of apertures formed in a second portion thereof, a tubular diaphragm disposed over the second portion of each member and affixed thereto in a sealed relation adjacent the margins of said respective second portion, a housing surrounding each tubular diaphragm having inlet and outlet port means, a work fluid disposed within each member, a piston disposed within each cylinder, a drive means for reciprocating said pistons in a phased operating sequence of less than l between the respective operating strokes thereof, valve means associated with each inlet and outlet port means for controlling the flow of a pumped fluid into each inlet port means as its respective piston moves in a first direction and for moving the pumped fluid outwardly of each outlet port means when its respective piston moves in an opposite direction, and inlet and outlet manifold means coupled respectively to the inlet and outlet ports of each pump unit, said inlet manifold being adapted to be coupled to a source of pumped fluid to provide a flow of pumped fluid in said outlet manifold in accordance with the phase operating sequence of said pump units.

9. The pump set forth in claim 7 and including pump body means, each of said tubular members and each of said housings being affixed to said pump body means and extending therefrom, each of said inlet and outlet port and manifold means being formed in said pump body means and communicating with their respective housing.

10. The pump set forth in claim 9 wherein said pump body means includes a central body member having said port means formed therein, all of said inlet port means being formed in a first portion of said central body member and the other port means being formed in a second portion thereof and first and second body members secured to said central body member and being disposed over said inlet and outlet and other port means, said first and second body members each having one of said manifold means formed therein.

11. The pump set forth in claim 10, and including a work fluid reservoir and passage means including a work fluid port for coupling each cylinder to said reservoir, each of said work fluid ports being uncovered by its respective piston as the latter moves toward a terminal position away from its diaphragm and being covered by said piston as the same moves toward its diaphragm whereby said cylinders will refill with work fluid during each stroke of its piston.

12. The pump set forth in claim 11, wherein said work fluid reservoir is connected to said drive means for lubricating the same wherein leakage of work fluid past said pistons also provides lubricating fluid for said pistons and said drive means.

13. A triplex chamber, piston actuated tubular diaphragm pump for pumping corrosive liquids such as saline water in which the pistons are isolated from the corrosive liquid comprising, inlet and outlet manifold means, three tubular chambers connected to and in liquid communication with the inlet and outlet manifold means, tubular diaphragm means disposed in each tubular chamber, said tubular diaphragms each defining an inner chamber inside the corresponding tubular chamber, a work fluid disposed in each chamber adapted to expand the associated tubular diaphragm thereby pumping the liquid through said multichamber pump, actuating piston means for successively actuating each tubular diaphragm in balanced phase sequence to obtain a uniform,

pressurized flow of liquid through said tubular diaphragm pump, a tubular support rod disposed within and extending through each tubular diaphragm means, each support rod having first and second end extensions and an intermediate perforated wall portion enclosed by the corresponding tubular diaphragm means, and means for securing the inlet and outlet manifold means and the tubular chambers together in a unitary assembly on the tubular support rods whereby said support rods act as tie rod means in addition to providing support for the associated tubular diaphragm means.

14. The apparatus of claim 13, in which the first end extension of each tubular support rod defines a cylinder housing the corresponding piston means.

15. The apparatus of claim 14, including fluid passage means interconnecting the cylinder with the second end extension, closure means for the fluid passage means in said second end extension, said closure means providing a fluid level at least equal in level to any other portion of the cylinder and interconnecting fluid passage means, whereby all air is readily displaced from the cylinders, the fluid passage means, and the tubular supports upon filling with work fluid.

16. The apparatus of claim 15, in which the tubular chambers comprise housing means defining the respective pump chambers, said inlet manifold being disposed adjacent one end of the assembled housing means, said outlet manifold disposed adjacent the other end of the housing means, enlarged shoulder means on the respective first end extensions of the tubular support rods, fastening means received on the second end extension of each tubular support rod for urging said inlet and outlet manifolds and said housing means firmly together between said enlarged shoulder means and said fastening means when said fastening means is advanced along the support rods towards the shoulder means.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N Dated January 25,

Richard W. Goeldner Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 8, after "lubricating" insert fluid For line 19, after "diaphragm" insert and 1ine3l, after "manifold" insert means line 33, after "manifold" insert means line 72, after "diaphragm" insert means 1 same column 6, line 75, after "diaphragm" insert means Signed and sealed this 3rd day of October 1972.

it i i 1 (SEAL) 1 Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents RM (10'69) uscoMM-Dc scan-P09 n U,$. GOVERNMENT PRINTING OFFICE: IBQ 35"3Jl. 

1. A diaphragm pump comprising an elongate tubular member, a cylinder formed in a first portion of said member, a plurality of apertures formed in a second portion of said member, a tubular diaphragm disposed over the second portion of said member and affixed thereto in a sealed relation adjacent the margins thereof, a housing surrounding said second portion and having inlet and outlet means, a work fluid disposed within said member, a piston disposed within said cylinder for reciprocating movement therein, valve means associated with said input and output means for controlling the flow of a pumped fluid outwardly from said housing through said outlet means as said piston moves toward said diaphragm to expand the same and inwardly through said inlet means when said piston moves away from said diaphragm.
 2. The pump set forth in claim 1 and including a pump body, said tubular member and said housing being affixed to said pump body and extending therefrom, said inlet and outlet means comprising port means formed in said pump body and communicating with the interior of said housing.
 3. The pump set forth in claim 2 wherein said cylinder is formed in one end of said member which is affixed to said pump body, said second portion extending away from said housing, operating means for moving said piston within said cylinder.
 4. The pump set forth in claim 3 wherein said pump body includes a central body member, a first one of said port means being formed in a first portion of said central body member and the second port means being formed in a second portion thereof and first and second body members secured to said central body member and being disposed over said first and second port means respectively.
 5. The pump set forth in claim 3, and including a work fluid reservoir, and passage means including a work fluid port for coupling said cylinder to said reservoir, said work fluid port being uncovered by said piston as the latter moves toward a terminal position away from said diaphragm and being covered by said piston as the same moves toward said diaphragm whereby said cylinder will refill with work fluid during each stroke of said piston.
 6. The pump set forth in claim 5, wherein said work fluid reservoir is connected to said operating means for lubricating the same wherein leakage of work fluid past said piston also provides lubricating fluid for said piston and operating means.
 7. The pump set forth in claim 5 and including three pump units, said drive means being operative to move the piston of said pump means in a balanced phase sequence of 120*.
 8. A multiple unit pump assembly, each pump unit including an elongate tubular member, a cylinder formed in a first portion of each member and a plurality of apertures formed in a second portion thereof, a tubular diaphragm disposed over the second portion of each member and affixed thereto in a sealed relation adjacent the margins of said respective second portion, a housing surrounding each tubular diaphragm and having inlet and outlet port means, a work fluid disposed within each member, a piston disposed within each cylinder, a drive means for reciprocating said pistons in a phased operating sequence of less than 180* between the respective operating strokes thereof, valve means associated with each inlet and outlet port means for controllIng the flow of a pumped fluid into each inlet port means as its respective piston moves in a first direction and for moving the pumped fluid outwardly of each outlet port means when its respective piston moves in an opposite direction, and inlet and outlet manifold means coupled respectively to the inlet and outlet ports of each pump unit, said inlet manifold means being adapted to be coupled to a source of pumped fluid to provide a flow of pumped fluid in said outlet manifold means in accordance with the phase operating sequence of said pump units.
 9. The pump set forth in claim 7 and including pump body means, each of said tubular members and each of said housings being affixed to said pump body means and extending therefrom, each of said inlet and outlet port and manifold means being formed in said pump body means and communicating with their respective housing.
 10. The pump set forth in claim 9 wherein said pump body means includes a central body member having said port means formed therein, all of said inlet port means being formed in a first portion of said central body member and the other port means being formed in a second portion thereof and first and second body members secured to said central body member and being disposed over said inlet and outlet and other port means, said first and second body members each having one of said manifold means formed therein.
 11. The pump set forth in claim 10, and including a work fluid reservoir and passage means including a work fluid port for coupling each cylinder to said reservoir, each of said work fluid ports being uncovered by its respective piston as the latter moves toward a terminal position away from its diaphragm and being covered by said piston as the same moves toward its diaphragm whereby said cylinders will refill with work fluid during each stroke of its piston.
 12. The pump set forth in claim 11, wherein said work fluid reservoir is connected to said drive means for lubricating the same wherein leakage of work fluid past said pistons also provides lubricating fluid for said pistons and said drive means.
 13. A triplex chamber, piston actuated tubular diaphragm pump for pumping corrosive liquids such as saline water in which the pistons are isolated from the corrosive liquid comprising, inlet and outlet manifold means, three tubular chambers connected to and in liquid communication with the inlet and outlet manifold means, tubular diaphragm means disposed in each tubular chamber, said tubular diaphragms each defining an inner chamber inside the corresponding tubular chamber, a work fluid disposed in each chamber adapted to expand the associated tubular diaphragm means thereby pumping the liquid through said multichamber pump, actuating piston means for successively actuating each tubular diaphragm means in balanced phase sequence to obtain a uniform, pressurized flow of liquid through said tubular diaphragm pump, a tubular support rod disposed within and extending through each tubular diaphragm means, each support rod having first and second end extensions and an intermediate perforated wall portion enclosed by the corresponding tubular diaphragm means, and means for securing the inlet and outlet manifold means and the tubular chambers together in a unitary assembly on the tubular support rods whereby said support rods act as tie rod means in addition to providing support for the associated tubular diaphragm means.
 14. The apparatus of claim 13, in which the first end extension of each tubular support rod defines a cylinder housing the corresponding piston means.
 15. The apparatus of claim 14, including fluid passage means interconnecting the cylinder with the second end extension, closure means for the fluid passage means in said second end extension, said closure means providing a fluid level at least equal in level to any other portion of the cylinder and interconnecting fluid passage means, whereby all air is readily displaced from the cylinders, the fluid passage means, and the tubular supporTs upon filling with work fluid.
 16. The apparatus of claim 15, in which the tubular chambers comprise housing means defining the respective pump chambers, said inlet manifold being disposed adjacent one end of the assembled housing means, said outlet manifold disposed adjacent the other end of the housing means, enlarged shoulder means on the respective first end extensions of the tubular support rods, fastening means received on the second end extension of each tubular support rod for urging said inlet and outlet manifolds and said housing means firmly together between said enlarged shoulder means and said fastening means when said fastening means is advanced along the support rods towards the shoulder means. 